Wireless battery charging system for existing hearing aids using a dynamic battery and a charging processor unit

ABSTRACT

A rechargeable battery which may be used with most presently available hearing aids (or other appliances) with no modification to the existing hearing aid is needed in order to use the described wireless charging system. The battery may be known a &#34;Dynamic battery&#34; as the battery is actively charged by means of an inductor circuit built into the battery housing itself or added onto the battery. The hearing aid may simply be placed within the charger housing (or cradle) to charge the battery. No electrical connection by either wires or electrical contacts is needed to recharge the battery, which is located inside the hearing aid housing. Moreover, the battery need not be removed from the hearing aid (or other appliance).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional Application of U.S. patent applicationSer. No. 10/080,240, filed on Feb. 22, 2002 now U.S. Pat. No. 6,498,455,incorporated herein by reference. The present application also claimspriority from Provisional U.S. Patent Application No. 60/270,147 filedon Feb. 22, 2001, also incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a rechargeable battery particularly foruse in hearing aids or the like. In particular, the present invention isdirected toward a hearing aid battery with a built-in inductive chargingcoil for recharging the hearing aid battery in situ.

BACKGROUND OF THE INVENTION

Each hearing aid needs a battery power source to provide electricalcurrent to its components. In Prior Art hearing aids, standardnon-rechargeable batteries are used. Such batteries may last less thanseven days before going dead. Constant replacement of hearing aidbatteries is time consuming, expensive, environmentally unfriendly, andin many cases, a trying task.

Because of the small physical size of the batteries and the hearing aidhousing, a large number of individuals who could benefit from the use ofhearing aids are unable to do so because of their inability to open andclose the access doors to the battery compartment in the hearing aid. Itis very hard for most people, and impossible for others, particularlythe elderly, who make up a large portion of hearing aid users.

Rechargeable batteries are known in the art. Various types of chemicalcompounds and mixtures for such batteries are know (e.g., Nickel andCadmium, or NiCad). However, such Prior Art rechargeable batteriesusually require removal of the battery or battery pack in order tocharge the battery, or require the use of electrical contacts on theappliance for battery charging.

For example, cellular phones are generally provided with a removablebattery pack which may be either charged while attached to the phone, orafter removal, through use of a “charging stand”. Cordless phones mayuse a built-in (e.g., hard wired) battery pack which may be charged whenthe phone is placed in its cradle. While such designs work well forfairly large appliances such as cellular phones or cordless phones, theuse of external electrical contacts or removable battery packs may notbe suitable for some applications, such as hearing aids.

External electrical connections may be difficult to physically implementon an object as small as a hearing aid, and moreover, may present ashock hazard to the user (as well as potential corrosion problems whenplaced in contact with the alimentary canal). Removable battery packspresent the same or similar problem to prior art hearing aids asdescribed above—such a removable pack would be so small as to make itdifficult, if not impossible, for a user to manipulate (especiallyelderly users which comprise a large majority of hearing aid customers).In addition, providing a removable battery pack would necessitate seamlines on the hearing aid housing and electrical contacts, both of whichmay increase the size and cost of the hearing aid or present sharp edgeswhich are unacceptable in an in-the-ear design.

Rechargeable batteries in standard sizes (e.g., “D”, “C”, “AA” and“AAA”) are also known in the art and may be purchased as substitutes forstandard non-rechargeable batteries. Generally, such rechargeablebatteries do not last as long as a comparative alkaline battery beforerecharging is required. When recharging is required, the batteries mustgenerally be removed from their battery compartment (unless a separatecharging port and circuit are provided) and placed in a stand-alonecharger.

Presuming that a rechargeable battery could be provided for appliancesas small as a hearing aid (or the like), such a solution would not solvethe fundamental underlying problem of battery insertion and removal. Incontrast, such a solution would only increase the frequency at which ahearing aid battery would need to be removed and replaced.

Inductive chargers are known in the art for use with small appliancessuch as electric toothbrushes and the like. Current passes through aninductive coil in a charging stand. A current is induced in a matingcoil in the appliance when the appliance is placed in the chargingstand. This current is then used to charge the batteries within theappliance. Such inductive chargers are particularly useful forappliances used in wet environments such as electric toothbrushes andother dental care items. Such chargers, however, have the advantage ofbeing able to mechanically locate the appliance in a predeterminedorientation (e.g., via a tab or other locating device) in relationshipto the charging coil such that the appliance and charger are at optimalposition for inducing current.

One approach to solving the hearing aid battery problem would be toapply such a Prior Art inductive charging system to a hearing aid (orother small appliance) design. Mattatall, U.S. Pat. No. 4,379,988,issued Apr. 12, 1983 and incorporated herein by reference, disclosessuch a design. However, to implement such a design would require thatthe hearing aid manufacturer re-design the hearing aid (or other smallappliance) to include the necessary charging circuitry. To the best ofapplicant's knowledge, no hearing aid designer has yet undertaken such adesign change, and no commercial embodiment of the Mattatall Patent hasyet been placed into production. Mattatall also discloses (Col. 5, lines2-12) the use of an LED for rectifying current and for indicating to theuser when the hearing aid is in optimal position for charging. Hearingaids, being very small, may be difficult to properly orient withrelationship to an inductive charger. Thus, Mattatall uses his LED toallow the user to manually position the hearing aid for chargingpurposes.

Even if such a design were commercially available, it would stillpresent problems to users. For example, existing hearing aid users wouldbe forced to discard their present hearing aids and purchase a new,rechargeable model, if such a recharging feature were desired. Moreover,most rechargeable appliances (as in Mattatall) feature “built-in”batteries, such that when the battery is no longer capable of beingcharged, the entire appliance must be discarded. Moreover, it may bedifficult for users to manually position the hearing aid in the chargerfor optimal current induction.

Rohde, U.S. Pat. No. 5,959,433, issued Sep. 28, 1999, and incorporatedherein by reference, discloses battery pack for a laptop or the like,with an inductive charging circuit. The design of Rhode allows thebattery pack to be removed and placed on an inductive charger withoutthe need for physical electrical connections. There are several problemswith this design. To begin with, it is not cost-effective to install aninductive charging circuit in a battery pack which already containsexternal electrical contacts.

As illustrated in FIG. 2 of Rohde, the battery pack 14 is provided withexternal electrical contacts at one end. It makes little or no sense toincorporate a relatively expensive and complex inductive charger into abatter pack when the battery pack can be readily recharged throughinexpensive electrical contacts. Moreover, the inductive charging coilof Rohde appears to take up a substantial portion of the battery pack.

Moreover, the Rohde design appears to require that the battery pack beremoved before charging. As noted above, the use of removable batteriesor battery packs does not solve the fundamental problem with hearingaids and other small appliances where removal of the battery packpresents difficulty to the user. In addition, it does not appear thatthe device of Rohde would be scalable to something as small as a hearingaid.

Thus, a need still exists in the art to provide a method and apparatusfor recharging a battery for a hearing aid (or other small appliance)without requiring removal of the battery from the appliance, withoutrequire the use of external physical electrical contacts, and withoutrequiring the re-design of the appliance to incorporate such a chargingcircuit. The present invention solves all of these problems.

SUMMARY OF THE INVENTION

The object of the invention is to provide a user-friendly system ofrecharging existing hearing aid batteries, saving time, money andfrustration. Rechargeable batteries are available for a variety ofapplications, but have not been utilized in hearing aids. The inventionutilizes a wireless solution of charging a battery by inductivelycoupling energy between the battery and the charging unit. Therefore, noremoval of the battery from the hearing aid is necessary. The user maysimply place the hearing aid into the charging cradle at night forrecharge.

The present invention further provides an inductive charging circuitwithin the housing of a standard hearing aid battery cell. By placingthe inductive charging circuit within a standard hearing aid batterycell, a user can convert a Prior Art hearing aid which uses disposablebatteries into a rechargeable hearing aid, simply be substituting therechargeable battery/charger of the present invention for thenon-rechargeable battery. The hearing aid (or other small appliance) maythen be readily recharged without the need for battery removal.Moreover, the user need not remove the battery for months or even years.In addition, in an alternative embodiment, a novel charging station isprovided with a rotatable induction coil. The induction coil may beautomatically rotated by a controller until optimal current induction inthe hearing aid battery coil occurs. This feature allows the hearing aidto be charged regardless of its relative position to the charging stand.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective exploded view of the combined battery andinductive coil of the present invention showing the charging componentsin block diagram form.

FIG. 2 is a block diagram of a charging station for use with thecombined battery and inductive coil of FIG. 1.

FIG. 3 is a side view of the combined battery and inductive coil of thepresent invention illustrating how the inductive coil and chargingcircuit can be incorporated into a standard sized battery case.

FIG. 4 is a perspective exploded view of the combined battery andinductive coil of a second embodiment of the present invention showingthe charging components in block diagram form.

FIG. 5 is a side view of the combined battery and inductive coil of thesecond embodiment of the present invention illustrating how theinductive coil and charging circuit can be incorporated into a standardsized battery case.

DETAILED DESCRIPTION OF THE INVENTION

The Wireless Battery Charging System for hearing aids of the presentinvention may comprise two main components. The first of these is thecombined battery and inductive charging coil and associated electronicswhich is referred to in the present invention as a “dynamic battery”.FIG. 1 is a perspective exploded view of the combined battery andinductive coil of the present invention showing the charging componentsin block diagram form. FIG. 3 is a side view of the combined battery andinductive coil of the present invention illustrating how the inductivecoil and charging circuit can be incorporated into a standard sizedbattery case.

Referring to FIG. 3, the dynamic battery may include two components. Thefirst component is rechargeable battery portion 31 which may occupyabout 75% of the battery overall housing. The battery housing isdesigned to be the same shape and size of a conventionalnon-rechargeable battery for use in a hearing aid or other smallappliance such that the housing may be inserted into the hearing aid orother appliance without need to modify the appliance.

Again referring to FIG. 3, the second component of the dynamic batteryis integrated electrical inductor circuit 32 made up of a tunedresonance circuit. FIG. 1 is a perspective exploded view of theinductive component 32 of FIG. 1 of the present invention showing thecharging components in block diagram form. Electrical inductor component32 of FIG. 3 may comprise a tuned resonance circuit including Coil 13and Capacitor 14 as well as a regulated charging circuit 15 utilizingcomponents such as surface mount resistors and regulators 14, 19, 18,and 17 to accommodate the small available space requirements of thedynamic battery.

The components of inductor circuit 32 of FIG. 3 may be mounted on a thinlayer of ceramic 16 as illustrated in FIG. 1 to provide a carriersurface for all discreet components or in other words to create a smallenough inductor hybrid to be placed inside the 25% of the overalldynamic battery housing. The wiring of the circuitry of FIG. 1 is notillustrated here, as such inductive charging circuits per se are knownin the art, as discussed above.

FIG. 2 is a block diagram of a charging station for use with thecombined battery and inductive coil of FIG. 1. The charging processorunit is a generator for controlling magnetic field lines. The chargingprocessor may comprise the following components. SMP (Switch Mode PowerSupply) power supply 21 provides the necessary current to the chargingprocessor and its electrical components. Other types of power suppliesmay also be used within the spirit and scope of the present invention.

Control circuit to control the charging process and its stages maycomprise digital control logic 22 containing a single chip processor anddiscreet components. Digital control logic 22 may monitor the chargingprocess and determine when the rechargeable battery is fully charged byuse of a timing mechanism or other means. Digital to analog converter 23may convert digital charging information into an analog signal drivingoutput stage 24, which powers an electromagnetic sending core 25.

Electromagnetic sending core 25 may comprise a motorized mechanismcombined with a shaft angle de-encoder 26 which in turn supports are-positioning mechanism for sending core 25. A digital display readout27 may provide information of the charging process as charging/charged.

The functionality of the overall system may now be described inconnection with FIGS. 1-5. If the dynamic battery is placed within rangeof the magnetic field lines produced by the charging processor, thebuilt-in tuned resonance circuit of the inductor component of thedynamic battery may absorb energy from the charging processor unit whichmay then be used to charge the battery component.

Since the physical size of the batteries charging component is verysmall, the position of the sending core toward the inducting circuit ofthe battery may be critical. The solution to this is a controlledpositioning system for the sending core. When a charging process isstarted, the sending core may be turned approximately 200 Degree in bothdirections via a motorized mechanism as illustrated in FIG. 2. Eachposition within a degree is reported to the CPU control logic 22utilizing shaft angle encoder/decoder 26. At the same time, drivercurrent (producing the magnetic field) for the sending core 25 isdigitized and measured by the CPU control logic 22. The tuned inductingcircuit of the battery will naturally absorb energy from the sendingcore magnetic field, which is measurable. CPU control logic 22 willdetermine the final position of sending core 25 based upon the drivercurrent measurement and realign the position of sending core 25 for anoptimal charging process.

Thus, the hearing aid with the battery of the present invention can beplaced in almost any orientation within a charging stand and still becharged. Unlike Prior Art inductive charging appliances, the hearing aidneed not be in a predetermined orientation. Unlike Mattatall, thehearing aid need not be reoriented manually based upon LED intensity.The user need only place the hearing aids (or other small appliances) inthe charging stand and turn the unit on.

FIG. 4 is a perspective exploded view of the combined battery andinductive coil of a second embodiment of the present invention showingthe charging components in block diagram form. FIG. 5 is a side view ofthe combined battery and inductive coil of the second embodiment of thepresent invention illustrating how the inductive coil and chargingcircuit can be incorporated into a standard sized battery case. Thissecond embodiment of the present invention may be substituted for thefirst embodiment of the present invention with respect to FIG. 2.

Referring to FIG. 5, the dynamic battery may comprise two components.The first component is rechargeable battery component 51 which mayoccupy about 95% of the battery overall housing. The battery housing isdesigned to be the same shape and size of a conventionalnon-rechargeable battery for use in a hearing aid or other smallappliance such that the housing may be inserted into the hearing aid orother appliance without need to modify the appliance.

Again referring to FIG. 5, the second component of the dynamic batteryis integrated electrical inductor circuit portion 52 made up of a tunedresonance circuit. Note that in this second embodiment, the inductorportion takes up less space in the battery housing than the embodimentof FIGS. 1 and 3, leaving more room for battery portion 51.

FIG. 4 is a perspective exploded view of the combined battery andinductive coil of the present invention showing the charging componentsin block diagram form. Electrical inductor circuit 52 of FIG. 5 maycomprise a tuned resonance circuit including coil 52 and capacitor 54 aswell as a regulated charging circuit 55 utilizing components such assurface mount resistors and regulators 54, 59, 58, and 57 to accommodatethe small available space requirements of the dynamic battery.

The components of inductor circuit 52 of FIG. 5 may be mounted on anegative battery contact 56 as illustrated in FIG. 4 to provide acarrier surface for all discreet components or in other words to createa small enough inductor hybrid to be placed inside the 5% of the overalldynamic battery housing. The wiring of the circuitry of FIG. 4 is notillustrated here, as such inductive charging circuits per se are knownin the art, as discussed above.

As illustrated in FIG. 4, inductor coil 53 may comprise the lateralhousing of the overall battery case, or may be wound inside such a case.By providing inductor coil 53 in this manner, additional space is leftfor the battery, and the size of inductor coil 53 may be increased.Positive battery contact 51 may for another portion of the batteryhousing. In this manner, the battery portion of the present inventioncan be maximized and the inductive components further miniaturized andmade more compact.

While the preferred embodiment and various alternative embodiments ofthe invention have been disclosed and described in detail herein, it maybe apparent to those skilled in the art that various changes in form anddetail may be made therein without departing from the spirit and scopethereof.

For example, while disclosed herein as being applied to hearing aids andthe like, the present invention could also be applied to other batteryoperated appliances such as watches, cellular phones, Personal DigitalAssistants (PDAs), Flashlights, Toys, and the like. Battery sizes otherthan hearing aid batteries may be used (e.g., watch batteries, AAA, AA,C, D, and other sizes) without departing from the spirit and scope ofthe present invention.

We claim:
 1. A method of charging a small appliance placed in anarbitrary relationship to a charging stand, comprising the steps of:supplying current to a sending core magnetic coil, measuring current tothe sending core magnetic coil, inducing a current in a receivingmagnetic coil in the small appliance placed in an arbitrary relationshipto the charging stand, rotating the sending core magnetic coil through apredetermined arc of rotation while measuring the current to the sendingcore magnetic coil, determining an optimal position for the sending coremagnetic coil based upon measured current to the sending core magneticcoil, and locating the sending core magnetic coil at the determinedoptimal position so as to charge the small appliance.
 2. The method ofclaim 1, wherein the small appliance is provided with a rechargeablebattery and current induced in the receiving magnetic coil charges therechargeable battery.
 3. A charging stand for charging a small applianceplaced in an arbitrary relationship to a charging stand, said apparatuscomprising: means for supplying current to a sending core magnetic coil;means for measuring current to the sending core magnetic coil; means forinducing a current in a receiving magnetic coil in the small applianceplaced in an arbitrary relationship to the charging stand; means forrotating the sending core magnetic coil through a predetermined arc ofrotation while measuring the current to the sending core magnetic coil;means for determining an optimal position for the sending core magneticcoil based upon measured current to the sending core magnetic coil; andmeans for locating the sending core magnetic coil at the determinedoptimal position so as to charge the small appliance.
 4. The apparatusof claim 3, wherein the small appliance is provided with a rechargeablebattery and current induced in the receiving magnetic coil charges therechargeable battery.
 5. A method of charging a small rechargeablebattery-operated appliance placed in an arbitrary relationship to acharging stand, comprising the steps of: supplying current to a sendingcore magnetic coil so as to generate a magnetic field, measuring currentto the sending core magnetic coil, inducing a current in a receivingmagnetic coil from the magnetic field in the small appliance placed inan arbitrary relationship to the charging stand, rotating the sendingcore magnetic coil through a predetermined arc of rotation whilemeasuring the current to the sending core magnetic coil, determining anoptimal position for the sending core magnetic coil based upon measuredcurrent to the sending core magnetic coil, locating the sending coremagnetic coil at the determined optimal position, and charging therechargeable battery in the small appliance with the induced current. 6.A charging stand for charging a small rechargeable-battery-operatedappliance placed in an arbitrary relationship to a charging stand, saidapparatus comprising: sending core magnetic coil supplied with currentso as to generate a magnetic field; means for measuring current to thesending core magnetic coil; a receiving magnetic coil for inducingcurrent from the magnetic field in the small appliance placed in anarbitrary relationship to the charging stand; means for rotating thesending core magnetic coil through a predetermined arc of rotation whilemeasuring the current to the sending core magnetic coil; means fordetermining an optimal position for the sending core magnetic coil basedupon measured current to the sending core magnetic coil; and means forlocating the sending core magnetic coil at the determined optimalposition so as to charge the rechargeable battery in the smallappliance.
 7. A method of charging a small rechargeable battery placedin an arbitrary relationship to a charging stand, comprising the stepsof: supplying current to a sending core magnetic coil so as to generatea magnetic field, measuring current to the sending core magnetic coil,inducing a current in a receiving magnetic coil from the magnetic fieldin the rechargeable battery placed in an arbitrary relationship to thecharging stand, rotating the sending core magnetic coil through apredetermined arc of rotation while measuring the current to the sendingcore magnetic coil, determining an optimal position for the sending coremagnetic coil based upon measured current to the sending core magneticcoil, locating the sending core magnetic coil at the determined optimalposition, and charging the rechargeable battery with the inducedcurrent.
 8. A charging stand for charging a small rechargeable batteryplaced in an arbitrary relationship to a charging stand, said apparatuscomprising: sending core magnetic coil supplied with current so as togenerate a magnetic field; means for measuring current to the sendingcore magnetic coil; a receiving magnetic coil for inducing current fromthe magnetic field in the rechargeable battery placed in an arbitraryrelationship to the charging stand; means for rotating the sending coremagnetic coil through a predetermined arc of rotation while measuringthe current to the sending core magnetic coil; means for determining anoptimal position for the sending core magnetic coil based upon measuredcurrent to the sending core magnetic coil; and means for locating thesending core magnetic coil at the determined optimal position so as tocharge the rechargeable battery with the induced current.
 9. A method ofcharging a small rechargeable battery-operated appliance placed in anarbitrary relationship to a charging stand, comprising the steps of:supplying current to at least one sending core magnetic coil so as togenerate a magnetic field, measuring current to the at least one sendingcore magnetic coil, inducing a current in a receiving magnetic coil fromthe magnetic field in the small appliance placed in an arbitraryrelationship to the charging stand, determining an optimal position forthe at least one sending core magnetic coil based upon measured currentto the sending core magnetic coil, providing current to sending coremagnetic coil at the determined optimal position, and charging therechargeable battery in the small appliance with the induced current.10. A charging stand for charging a small rechargeable-battery-operatedappliance placed in an arbitrary relationship to a charging stand, saidapparatus comprising: at least one sending core magnetic coil suppliedwith current so as to generate a magnetic field; means for measuringcurrent to the at least one sending core magnetic coil; a receivingmagnetic coil for inducing current from the magnetic field in the smallappliance placed in an arbitrary relationship to the charging stand;means for determining an optimal position for the at least one sendingcore magnetic coil based upon measured current to the sending coremagnetic coil; and providing current to the sending core magnetic coilat the determined optimal position so as to charge the rechargeablebattery in the small appliance.
 11. A method of charging a smallrechargeable battery placed in an arbitrary relationship to a chargingstand, comprising the steps of: supplying current to at least onesending core magnetic coil so as to generate a magnetic field, measuringcurrent to the at least one sending core magnetic coil, inducing acurrent in a receiving magnetic coil from the magnetic field in therechargeable battery placed in an arbitrary relationship to the chargingstand, determining an optimal position for the at least one sending coremagnetic coil based upon measured current to the sending core magneticcoil, providing current to the sending core magnetic coil at thedetermined optimal position, and charging the rechargeable battery withthe induced current.
 12. A charging stand for charging a smallrechargeable battery placed in an arbitrary relationship to a chargingstand, said apparatus comprising: at least one sending core magneticcoil supplied with current so as to generate a magnetic field; means formeasuring current to the at least one sending core magnetic coil; areceiving magnetic coil for inducing current from the magnetic field inthe rechargeable battery placed in an arbitrary relationship to thecharging stand; means for determining an optimal position for the atleast one sending core magnetic coil based upon measured current to thesending core magnetic coil; and means for providing current to thesending core magnetic coil at the determined optimal position so as tocharge the rechargeable battery with the induced current.